The present invention relates to a vapor containment system, and particularly to a vapor containment system that is at least partially formed as part of a fuel tank.
Internal combustion engines are often used to power small equipment such as lawnmowers, tillers, snow throwers, and the like. Typically, these engines include a fuel system that supplies fuel for combustion. The fuel system includes a tank, in which fuel is stored for use. Generally, the volatility of the fuel allows a portion of the fuel to evaporate and mix with air within the tank. Changes in temperature, such as those between evening and daytime, as well as sloshing during use can cause an increase or a decrease in the amount of fuel vapor in the tank as well as an increase or a decrease in the pressure within the tank.
To accommodate these pressure changes, fuel tanks often include a vent such as a vented fuel cap. The vent allows the excess air and fuel vapor to escape the tank when the pressure increases, and also allows air to enter the tank when the pressure drops. Pressure within the fuel tank typically drops as fuel is drawn from the tank for use. However, the escape of fuel vapor reduces the fuel efficiency of the engine.